Aerodynamic control of aircraft



Aug. 4, 1936. Eq'A. STALKER AERODYNAMIC CONTROL OF AIRCRAFT Filed Dec.12, 1954 /N VEN 70/? sublect matter also contained Patented Aug. 4, 1936UNITED STATES PATENT OFFICE 14 Claims.

My invention relates to the aerodynamic control of aircraft throughmeans employing the modification of the boundary layer. It contains inmy pending application Serial No. 736,378, entitled Wings, and filedJuly 21, 1934. a

The objects of my invention are; first, to provide rolling momentsaccompanied by proper yawing moments; second, to extend the regime ofproper rolling and yawing moments beyond the normal range of angles ofattack. Other objects will appear from the description accompanying thedrawing.

I accomplish the above results by the devices illustrated in theaccompanying drawing in which- Figure 1 is a fragmentary top plan of theaircraft;

Figure 2 is a fragmentary top plan of the wing;

3 is a vertical section along the line 3-3 in Figure 1;

Figure 4 is a vertical section along the line 4-4 in Figure 1;

Figure 5 is a vertical section along the line 5-5 in Figures 1 or 2;

Figure 6 is a fragmentary vertical spanwise section of the fuselagelooking forward as indicated by-the section line 6-6 in Figure 1.

Similar numerals refer to similar parts throughout the several views.

Before proceeding with the description it is pertinent to discusscertain phases of the theory.

When an aircraft is banked by the use of an aileron or other device theyawing moment should be either neutral or slightly in the direction ofthe turn. That is, the rising wing should also have a tendency to thanthe declining wing. the reverse action.

When the aileron is depressed on one side of the airplane the liftincreases and along with it the induced drag'which is a function only of.the lift and the span. The aileron onthe opposite side is raisedand thelift is decreased with a resultant decrease of induced drag. These dragchanges are obviously of the wrong sign and cause an adverse yawingmoment. It is one object of this invention to remedy this defect.

Ailerons, as is well known, become ineifective Ordinary ailerons givenear the angle of maximum lift of the wing.

There is a very definite ultimate maximum lift for conventional wingsdue to a change in angle of attack or camber. An ordinary aileron givesa rolling moment by changing both the angle of attack and camber of theouter portion of the wing. If the wing lift angle a further increase inangle of attack by a depression of the aileron will not lead to afurther increase in lift.

It is known that the ultimate value of the maxi tion of flow advancemore rapidly is already flying at maximum mum lift for a conventionalwing can be increased by an energization of the boundary layer on thewing surface.

Briefly, energization of the boundary layer consists in'adding energy toit by blowing out a slot or by drawing the boundary layer into the winginterior. Both methods in effect suppress it. When blowing is used thejet should be directed rearward along the wing surface preferablytangentially thereto. The jet must not be discharged normal to thesurface because it will not then impart any velocity to the fluid in thedirecalong the surface. Such normal merelyinduce turbulence in the Ppose of boundary discharge will flow in opposition to the energizationto reduce it.

Any air discharged from a, slot into the boundary layer must have atleast as much energy or velocity as the boundary layer, more ifenergize.- tion is to take place. Air of lower energy or velocity whenmixed with the boundary layer will serve only to de-energize theboundary layer since after mixing; the energy or velocity per unitvolume will be less.

Referring to the figures, it will be noted that two means of energizingthe boundary layer are provided. The Wing I mounted on the fuselage 2has a through slot 3 from which a jet can issue and it also has thesurface slot 6. .Also, a suction or induction opening 6 is provided. Theinduction'slots 6, one on each side of the center of the span, arenormally open for the induction of theboundary layer for a neutralposition of the steering control. I 4

Within the wing I is a blower 1 whose rotation about the vertical shaft6 draws air from the upper compartment 9 and forces it into the lowercompartment l6. tion with the compartment l6 and so the fan dischargesthe inducted air out the surface slot rearward along the wing surface.

The suction or upper compartment 9 extends toward the wing tips to thevertical chordwise partition I 1 shown particularly in Figure 2. There.is also a compartment 9a. between the wing tip and the partition II.There is communication between the compartments 9 and 9a through thepartition II by means of the opening l2. See Figure 2 particularly sincethe partition opening is not shown in Figure 1 for the sake ofclearness.

The lower compartment l6 extends only to the partition II and at thissection the wing section changes smoothly from the convex lower surfacetype to a relatively fiat bottom type, as shown in Figure 5. This is notessential and either type of Wi g section could 5e used on any portionof the wing. The significant point is that the suction compartment 9:;is substantially distinc from the pressure compartment ll.

The slot 4 is in communicaangles of attack of the wing the flow followsthe wing contour and there is an increase of lift to roll the airplane.If the boundary layer energization available from the slots '3 and-6were not the upper surface.

present the flow would fail to follow the surface and no lift to rollthe airplane would be available.

The aileron is actuated by the conventional bell crank system and rods.As shown in Figures 2, 5 and 6 a bracket ll supports the double bellcrank it which is rotated by the crank arm I! a rod It extends rearwardto an articulated connection on the aileron which is hinged to the wingat l9. It is obvious that pushing on the rod It will raise the trailingedge of the aileron.

The wall of the through slot is perforated to form a passage 20 into thecompartment 9a and this passage is closeable by a flap 2| extendingspanwise along the length of the through slot. The flap is hinged at thetop at 22.

The flap is vactuated by a rod 23 extending from the-bell crank 24 tothe flap and joined at each end preferably by a ball and socket oruniversal Joint. A push on the rod It will cause the flap to swingforward into the through slot 3 as indicated by the dotted lines inFigure 5. It is to be remembered that the aileron is raised by. the pushon rod It so that the conditions are proper to cause the wing tip todecline. It is also to be recalled that for this condition an increasein drag is desirable.

The lift is decreased both by the up movement of the aileron and thespoilage of the flow over The flow is spoiled in the first place by theflow out of compartment 9:: through the slot 5 which deenergizes theboundary layer. Also, the flap 2| in the position shown dotted does nottouch the forward wall of the slot but actually permits a quantity ofair to pass which is made turbulent by the abrupt change in contour. The

advent of this air to the uppersurface also aids in de-energizing .thestruction of the flow decreases creases the drag.

The action of the fan 'I is not affected adversely by the admission ofair to the compartment to because the rod It carries a plunger 18a whichis thrust into the hole I: by the outward movement' of the rod 10. Thusthe full suction of the fan isdevoted to the opposite tip of the wing.

when the aileron is depressed to create a lift and rolling moment theflap 2| moves inward into compartment is but the passage of air isprevented by a lip formed on the lower edge. of the opening 2|. The flap2| also fits tightly against'suitable surfaces at its ends to prevent aninflow; into so. The lip 25 is sufliciently long to provide for the fulldown travel of the aileron. The push rod I6 is actuated by theconventional lever 26a, bell crank 26, rods I61: and 21, and arm 28connected to the torque tube 29 which is rotatable by the control stick30. a See Figure 6.

The fan is rotated either by the engine or the propeller acting as awindmill. This method of operation is described in my Patent No.1,913,644 granted June 13, 1933, entitled Means-of energizing theboundary layer on aircraft parts. Briefly, the method consists indriving the fan I by the engine through an over-running or dis boundarylayer. The dethe lift and inengageable clutch so that in case of enginefailure the fan I is rotatable by the propeller acting as a the rod l6.Ill'romthe upper surface.

windmill or turbine. By means of the clutch the turbine to fan drive isrelieved of the torque load of the dead engine. I

The slots extending along the major portion of the span insures theattainment of a high lifting capacity. The additional slots in the tipportions insures that the lift of these portions can be higher than thecentral portions; or in other words, that the lift of the tip portionscan be higher 'than the average lift for the whole wing. Hence when thewing as a whole is operating at maximum lift the tip portions areoperating at something less than their maximum possible lift.

It will now be clear that due to the modifications induced in theboundary layer the rolling moment may be large at large "angles ofattack. The increase in rolling moment over the conventional wing arisesboth from an increase and a decrease in the left over appropriateportions of the wing. Along with the there is an increase in drag so asto provide the proper yawing moments. The total result is to providepowerful control moments at all angles of attack which are especiallyuseful at the large angles of attack. spins which are the cause of mostaccidents begin. The control here provided is powerful enough and isavailable at the proper attit dc to eliminate this hazard of flight.

I use the term vane to represent any movable surface whether a part ofanother wing or not. I use the term tilting moment to refer to momentsgenerally.

decrease in lift 20 At the latter angles 25 Although I have illustrateda certain chordlifting capacity, a perforated upper surface or the wingto form a surface slot in communication with the wing interior, andcontrollable means to divert the flow in the through slot to the saidsurface slot. 2. In combination, a winghaving a through slot to conveythe relative wind from below to above the wing, a perforated upper.surface of the wing to form a slot in communication with the winginterior, and controllable means to place the said wing interior incommunication with the flow in the through slot and at least in partbarricade-the through slot to restrict its flow to 3. In combination inan aircraft, a wing having a through slot to convey the relative windfrom below to above the wing, walls defining a compartment on each sideof the longitudinal axis ofthe aircraft. a perforated upper surface ofthe wing to form slots leadinginto the compartments, meansto at leastpartially stop the flow in the through slot, and outflow through'atleast one of said surface slots in coordinated relation with saidineans'to stop the flow through the-through slot.

4. In combination in an aircraft, a wing having a through slot to conveythe relative wind from below to above the wing, a vane means to induce atilting .moment on the aircraft, walls defining meansto cause an acompartment on each side of the longitudinal axis of the aircraft, aperforated upper surface of the wing to form slots leading into thecompartments', means to at least partially stop theflow in the throughslot; and means to cause an outflow through at least one of said surfaceslots in coordinated relationship with said means to stop the flowthrough the through slot and with the said'vane means.

5. In an aircraft, a steering mechanism, a wing having a through slot oneach side of the lon gitudinal axis of the aircraft to convey therelative wind from below to above the wing, a perforated upper surfaceof the wing to form a surface slot in communication with the winginterior, and means controllable by the steering mechanism to place thewing interior in communication with the flow in the through slot on oneside of said axis to admit a fiow to the surface slot to create a momenton the aircraft.

6. In combination in an aircraft, a wing having an upper surfacedischarge slot formed for the discharge of fluid rearward with respectto the direction of flight and along the wing sur .face, a means toconvey a flow to the slot for discharge therefrom, a perforated uppersurface to form a second slot on each side of the longitudinal axis ofthe'aircraft in communication with the wing interior, and means tocontrol communication between the flow to the said discharge slot and atleast-one of the said second 'slots so as to create a rolling moment onthe aircraft, said second slots being directed away from the wing uppersurface behind the slot to destroy the local lift by the discharge offluid.

7. In combination in an aircraft, a wing having a control compartmentnear each lateral extremity and an energization compartment,

. means of communication between the control compartment and theenergization compartment, a perforated upper surface of the wing to formslots leading into said control and energization compartments, means toadmit air to a control compartmentfor passage out its surface slot, andcontrollable means to at least partially stop communication between thecontrol compartnient and said. energization compartment during the saidadmission of air.

8. In combination in an aircraft, a wing having -a control compartmentnear each lateral extremity and an energiz'ation compartment,

means of communication between the controlcompartment and theenergization compartment, a perforated upper surface of the wing to formslots leading into said control and energization compartments, meansto'admit air to a. control compartment for passage out its surface slot,and means to substantially prevent' the said admission of air whilethere is substantial communication between the energizationcompartmentand said control compartments.

9. In combination in an aircraft a wing having" a first, upper surfaceslot, a perforated upper;

surface to form a second slot on each side of the longitudinal axis ofthe aircraft 'in communication with the wing interior, means ofcommunication between the first and second slots, and means to controlcommunication between the first slot and at least one '01 the saidsecond slots to create a moment on the aircraft.

10. In an aircraft, a wing to support it and having in its surface aspanwise discharge slot on each side'of the longitudinal axis of theaircraft, said wing having a perforated upper surface to form inductionslots extending spanwise on each side of said axis, means providing fora flow of fluid through said slots, and controllable means to govern theflow of fluid through the slots differentially both with respect 'toslots on opposite sides of the said axis and with respect to thedischarge and induction slots.

11. In combination in an aircraft, a wing having compartments onopposite sides of the longitudinal axis of the aircraft and a cell and aperforated upper surface of the wing to form a slot in communicationwith each compartment for use in energizing the boundary layer, means toalter. the air pressure in the cell, and controllable means to establishcommunication between a compartment on one side of said axis and thecell and to admit air to the tip compartment on the opposite side ofsaid axis for discharge out the surface slot.

12. In an aircraft, a Wing having a hollow interior within at each wingtip and at least two chordwise-spaced spanwise slots in the uppersurface near each wing tip, means providing for a flow of fluid throughsaid slots, an aileron near each wing extremity, means of communicationbetween chordwise-spaced slots at the same wing tip through the winginterior, and controllable means to suppress the said communicationoperable in coordination withthe depression of the trailing edge of saidaileron.

13. In an aircraft in combination a wing having a hollow interior andtwo chordwisespaced spanwise slots in the upper surface near each wingtip, at least one inlet opening directed roll inducing device to raisethe wing tip having said closed communication between the slots, saidcombination providing effective energization of the boundary layer ofthe wing to cooperate with the action of said roll inducing device.

14. In an aircraft, a wing having a hollow interior within at each wingtip and at least two chordwise-spaced spanwise slots in the uppersurface near each wing tip, means providing for a flow of fluid throughsaid slots, an aileron near each wing extremity and controllable meansto establish communication between two-chordwise-spaced slots throughthe wing interior at a wing tip in coordination with an upward movementof the trailing edge of the aileron at the same wing tip as the slotsand to substantially suppress said communication for a depression of thetrailing edge of said aileron.

EDWARD A. STALKER.

